send() -- send message from connected socket

SYNOPSIS

#include <sys/socket.h>

int send(int s, const void *msg, size_t len, int flags);

The send() function initiates transmission of a message from the specified socket to its peer. The send() function sends a message only when the socket is connected (including when the peer of the connectionless socket has been set via connect()).

The length of the message to be sent is specified by the len argument. If the message is too long to pass through the underlying protocol, send() fails and no data is transmitted.

Successful completion of send() does not guarantee delivery of the message. A return value of -1 indicates only locally detected errors.

If space is not available at the sending socket to hold the message to be transmitted and the socket file descriptor does not have O_NONBLOCK set, send() blocks until space is available. If space is not available at the sending socket to hold the message to be transmitted and the socket file descriptor does have O_NONBLOCK set, send() fails with EWOULDBLOCK. The select() function can be used to determine when it is possible to send more data.

flags may be used to influence the behavior of the function invocation beyond the options specified for the associated socket. That is, the semantics of this function are determined by the socket options and the flags parameter. The latter is constructed by ORing any of the following values:

MSG_DONTROUTE: Specifies that the data should not be subject to routing.
MSG_OOB: Send out-of-band data (stream-style socket such as SOCK_STREAM only).

PARAMETERS

s: Specifies a socket descriptor to use for the send.
msg: Points to the buffer containing message to send.
len: Specifies the length of the message in bytes.
flags: Lets the sender control the way data is sent.

RETURN VALUES

If successful, send() returns the numbers of characters sent. If an error occurs, it returns -1 and sets errno to one of the following:

EBADF: s is an invalid descriptor.
ECONNABORTED: Connection was aborted due to timeout or other failure.
ECONNRESET: Connection was forcibly reset by the peer.
EFAULT: msg points to an unreadable location.
EHOSTUNREACH: The remote host cannot be reached from this host at this time.
EINVAL: The socket has not been bound with bind(), or an unknown flag was specified, or MSG_OOB was specified for a socket with SO_OOBINLINE enabled.
EINTR: A signal interrupted the call.
ENETDOWN: The network subsystem has failed.
ENOBUFS: No buffer space is available.
ENOTCONN: The socket is not connected.
ENOTSOCK: s is not a socket descriptor.
EMSGSIZE: Message size is too big to be sent atomically.
EOPNOTSUPP: MSG_OOB was specified, but the socket is not stream style such as type SOCK_STREAM, out-of-band data is not supported in the communication domain associated with this socket, or the socket is unidirectional and supports only receive operations.
ESHUTDOWN: The socket has been shutdown; it is not possible to send() on a socket after shutdown() has been invoked with how set to SD_SEND or SD_BOTH.
ETIMEDOUT: Connection has been dropped, because of a network failure or because the system on the other end went down without notice.
EWOULDBLOCK: s is nonblocking and send() would block.

send()
send message from connected socket

Function

SYNOPSIS

DESCRIPTION

PARAMETERS

RETURN VALUES

CONFORMANCE

MULTITHREAD SAFETY LEVEL

PORTING ISSUES

AVAILABILITY

SEE ALSO

send() send message from connected socket

Function

send()
send message from connected socket